Expanded polystyrene (EPS) geofoam is increasingly used in retaining structures as a compressible inclusion to reduce lateral earth pressures. However, the complex interactions among soil, EPS, and wall components—together with the limitations of analytical and numerical approaches—pose significant challenges in accurately predicting lateral pressures on rigid retaining walls with geofoam inclusions. This study introduces an intelligent hybrid Sparrow Search Algorithm–Machine Learning (SSA–ML) framework to overcome these deficiencies through autonomous hyperparameter optimization, interpretability enhancement, and uncertainty quantification. Six ML models—Generalized Neural Regression (GNRR), Support Vector Machine (SVM), Extreme Learning Machine (ELM), Decision Tree (DT), Random Forest (RF), and Multilayer Perceptron (MLP)—were optimized using SSA based on a comprehensive database compiled from experimental and numerical studies. Model performance was systematically assessed through K ‐fold cross‐validation and comparative analysis. The kernel density estimation (KDE) method was applied to generate probabilistic interval predictions, thereby quantifying the inherent uncertainty in the modeling process. Furthermore, the SHapley Additive exPlanations (SHAP) approach was employed to interpret the influence and directionality of key parameters on predicted lateral pressures. Results demonstrate that the proposed SSA–MLP model achieves superior predictive accuracy and robustness compared to other benchmark models, while maintaining clear physical interpretability. This hybrid, interpretable, and uncertainty‐aware framework provides a reliable data‐driven tool for analyzing lateral earth pressures on soil–EPS–wall systems and offers new insights for the design and optimization of compressible inclusion retaining walls.
{"title":"Hybrid Machine Learning and Metaheuristic Optimization Framework for Predicting Lateral Earth Pressures on Rigid Retaining Walls With Geofoam Inclusions in Sand Backfill","authors":"Shi Wang, Junjie Wang, Jie Huang, Yuyan Chen","doi":"10.1002/nag.70213","DOIUrl":"https://doi.org/10.1002/nag.70213","url":null,"abstract":"Expanded polystyrene (EPS) geofoam is increasingly used in retaining structures as a compressible inclusion to reduce lateral earth pressures. However, the complex interactions among soil, EPS, and wall components—together with the limitations of analytical and numerical approaches—pose significant challenges in accurately predicting lateral pressures on rigid retaining walls with geofoam inclusions. This study introduces an intelligent hybrid Sparrow Search Algorithm–Machine Learning (SSA–ML) framework to overcome these deficiencies through autonomous hyperparameter optimization, interpretability enhancement, and uncertainty quantification. Six ML models—Generalized Neural Regression (GNRR), Support Vector Machine (SVM), Extreme Learning Machine (ELM), Decision Tree (DT), Random Forest (RF), and Multilayer Perceptron (MLP)—were optimized using SSA based on a comprehensive database compiled from experimental and numerical studies. Model performance was systematically assessed through <jats:italic>K</jats:italic> ‐fold cross‐validation and comparative analysis. The kernel density estimation (KDE) method was applied to generate probabilistic interval predictions, thereby quantifying the inherent uncertainty in the modeling process. Furthermore, the SHapley Additive exPlanations (SHAP) approach was employed to interpret the influence and directionality of key parameters on predicted lateral pressures. Results demonstrate that the proposed SSA–MLP model achieves superior predictive accuracy and robustness compared to other benchmark models, while maintaining clear physical interpretability. This hybrid, interpretable, and uncertainty‐aware framework provides a reliable data‐driven tool for analyzing lateral earth pressures on soil–EPS–wall systems and offers new insights for the design and optimization of compressible inclusion retaining walls.","PeriodicalId":13786,"journal":{"name":"International Journal for Numerical and Analytical Methods in Geomechanics","volume":"3 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145786040","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Cao Zhisong, Zhang Xiaobo, Ma Yongli, Yao Chi, Yang Jianhua, Ye Zhiwei, Jiang Shuihua
The bedding planes in layered rock masses are critical structures that control strength and stability. This study systematically investigates the strength and deformation characteristics of layered rock under different confined pressures using the FDEM method. Based on the global embedded cohesive element in Abaqus, the differentiated characterization of bedding planes and rock matrix was achieved, and numerical specimens of layered rock samples were constructed. To comprehensively reveal the mesoscopic failure mechanisms of layered rock under different confined pressures, the precise discrimination of crack dynamic thresholds based on material properties was achieved through Python. Simultaneously, the damage distribution of layered rock is obtained, which shows the spatial distribution of shear and tension damage intuitively. The results show that the compressive strength exhibits U‐shaped with the bedding inclination. The compressive strength, elastic modulus, and peak strain demonstrate an approximately linear relationship with the increase in confined pressure. The new discriminant threshold obtained by the study can effectively distinguish the damage modes, and under different confined pressures, the proportion of crack types and the proportion of cracks at the matrix and bedding plane are significantly dependent on the bedding inclination. Meanwhile, the failure mechanism of the samples can be effectively characterized by the spatial distribution characteristics of shear and tension damage. Finally, the applicability of the proposed method is verified by comparing the results with published literature.
{"title":"Study of Anisotropic Behavior and Failure Characteristics of Layered Rock Based on Finite‐Discrete Element Method","authors":"Cao Zhisong, Zhang Xiaobo, Ma Yongli, Yao Chi, Yang Jianhua, Ye Zhiwei, Jiang Shuihua","doi":"10.1002/nag.70207","DOIUrl":"https://doi.org/10.1002/nag.70207","url":null,"abstract":"The bedding planes in layered rock masses are critical structures that control strength and stability. This study systematically investigates the strength and deformation characteristics of layered rock under different confined pressures using the FDEM method. Based on the global embedded cohesive element in Abaqus, the differentiated characterization of bedding planes and rock matrix was achieved, and numerical specimens of layered rock samples were constructed. To comprehensively reveal the mesoscopic failure mechanisms of layered rock under different confined pressures, the precise discrimination of crack dynamic thresholds based on material properties was achieved through Python. Simultaneously, the damage distribution of layered rock is obtained, which shows the spatial distribution of shear and tension damage intuitively. The results show that the compressive strength exhibits U‐shaped with the bedding inclination. The compressive strength, elastic modulus, and peak strain demonstrate an approximately linear relationship with the increase in confined pressure. The new discriminant threshold obtained by the study can effectively distinguish the damage modes, and under different confined pressures, the proportion of crack types and the proportion of cracks at the matrix and bedding plane are significantly dependent on the bedding inclination. Meanwhile, the failure mechanism of the samples can be effectively characterized by the spatial distribution characteristics of shear and tension damage. Finally, the applicability of the proposed method is verified by comparing the results with published literature.","PeriodicalId":13786,"journal":{"name":"International Journal for Numerical and Analytical Methods in Geomechanics","volume":"16 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145770625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Muhammad Kamran, Hongyuan Liu, Daisuke Fukuda, Haoyu Han, Di Wu, Qianbing Zhang, Shuhong Wang, Andrew Chan
Finite–discrete element method (FDEM) has become a widely recognised numerical method for simulating the fracturing behaviour of materials under various loading conditions. However, the substantial computational cost of three‐dimensional (3D) FDEM has led to a marked imbalance: extensive research exists on two‐dimensional (2D) FDEM, while studies on 3D FDEM remain limited. This study investigates the dynamic fracture behaviours of rocks under multiaxial static and dynamic coupled loads, utilising a self‐developed 3D FDEM parallelised based on a general‐purpose graphics processing unit (GPGPU). The 3D FDEM incorporates both intrinsic and extrinsic cohesive zone models (ICZM and ECZM) as well as various contact interaction algorithms to facilitate robust simulation of a full‐scale triaxial Hopkinson pressure bar (Tri‐HB) testing system. Dynamic uniaxial and biaxial compression (UC and BC) tests within the Tri‐HB framework are modelled with different combinations of cohesive zone models and contact algorithms, and the results are compared against each other and against laboratory experiments reported in the literature. The simulations demonstrate that the 3D FDEM with all these models and algorithms can reasonably capture the stress wave propagations in both metal bars and rocks as well as the primary dynamic fracturing behaviours of rocks under the coupled static and dynamic loads. However, computing accuracy and efficiency vary across model combinations. Overall, the 3D FDEM with the ECZM achieves the highest accuracy and efficiency.
{"title":"Insights Into the Dynamic Fracturing Behaviours of Rocks Under Multiaxial Static and Dynamic Coupled Loads Through 3D FDEM With Various Contact Algorithms and Cohesive Zone Models","authors":"Muhammad Kamran, Hongyuan Liu, Daisuke Fukuda, Haoyu Han, Di Wu, Qianbing Zhang, Shuhong Wang, Andrew Chan","doi":"10.1002/nag.70212","DOIUrl":"https://doi.org/10.1002/nag.70212","url":null,"abstract":"Finite–discrete element method (FDEM) has become a widely recognised numerical method for simulating the fracturing behaviour of materials under various loading conditions. However, the substantial computational cost of three‐dimensional (3D) FDEM has led to a marked imbalance: extensive research exists on two‐dimensional (2D) FDEM, while studies on 3D FDEM remain limited. This study investigates the dynamic fracture behaviours of rocks under multiaxial static and dynamic coupled loads, utilising a self‐developed 3D FDEM parallelised based on a general‐purpose graphics processing unit (GPGPU). The 3D FDEM incorporates both intrinsic and extrinsic cohesive zone models (ICZM and ECZM) as well as various contact interaction algorithms to facilitate robust simulation of a full‐scale triaxial Hopkinson pressure bar (Tri‐HB) testing system. Dynamic uniaxial and biaxial compression (UC and BC) tests within the Tri‐HB framework are modelled with different combinations of cohesive zone models and contact algorithms, and the results are compared against each other and against laboratory experiments reported in the literature. The simulations demonstrate that the 3D FDEM with all these models and algorithms can reasonably capture the stress wave propagations in both metal bars and rocks as well as the primary dynamic fracturing behaviours of rocks under the coupled static and dynamic loads. However, computing accuracy and efficiency vary across model combinations. Overall, the 3D FDEM with the ECZM achieves the highest accuracy and efficiency.","PeriodicalId":13786,"journal":{"name":"International Journal for Numerical and Analytical Methods in Geomechanics","volume":"51 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145770626","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We investigate splitting schemes based on the fixed‐stress sequential approach for poroelastodynamic problems. To assess numerical stability, we perform the von Neumann stability analysis on several fixed‐stress schemes for poroelastodynamics, including staggered, stabilized, and iterative methods. Our analysis reveals that while the staggered fixed‐stress method is unconditionally stable for poroelastostatics, this unconditional stability does not extend to poroelastodynamics due to the presence of the second‐order time derivative in the geomechanics wave equation. Specifically, the staggered method becomes unstable when the Courant number falls below unity, indicating a lower bound on the time step size required for stability in poroelastodynamic simulations. The stabilized method, which incorporates an additional stabilization term, maintains numerical stability across the full range of Courant numbers. However, it suffers from limited convergence and reduced accuracy, particularly at low Courant numbers. In contrast, the iterative fixed‐stress method consistently converges to the monolithic solution, regardless of the Courant number, provided that full iteration is performed. Numerical tests validate these stability estimates and confirm agreement with the von Neumann stability analysis.
{"title":"The von Neumann Stability Analysis of the Fixed‐Stress Schemes in Poroelastodynamics","authors":"Jihoon Kim, Sanghyun Lee, Mary F. Wheeler","doi":"10.1002/nag.70182","DOIUrl":"https://doi.org/10.1002/nag.70182","url":null,"abstract":"We investigate splitting schemes based on the fixed‐stress sequential approach for poroelastodynamic problems. To assess numerical stability, we perform the von Neumann stability analysis on several fixed‐stress schemes for poroelastodynamics, including staggered, stabilized, and iterative methods. Our analysis reveals that while the staggered fixed‐stress method is unconditionally stable for poroelastostatics, this unconditional stability does not extend to poroelastodynamics due to the presence of the second‐order time derivative in the geomechanics wave equation. Specifically, the staggered method becomes unstable when the Courant number falls below unity, indicating a lower bound on the time step size required for stability in poroelastodynamic simulations. The stabilized method, which incorporates an additional stabilization term, maintains numerical stability across the full range of Courant numbers. However, it suffers from limited convergence and reduced accuracy, particularly at low Courant numbers. In contrast, the iterative fixed‐stress method consistently converges to the monolithic solution, regardless of the Courant number, provided that full iteration is performed. Numerical tests validate these stability estimates and confirm agreement with the von Neumann stability analysis.","PeriodicalId":13786,"journal":{"name":"International Journal for Numerical and Analytical Methods in Geomechanics","volume":"23 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145765387","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Qingci Qin, Chaoquan Luo, Kegang Li, Fa Dong, Naeem Abbas
Fractures are one of the most critical factors influencing the mechanical properties of rocks. To explore the quantitative description method of fracture networks in natural rock masses and achieve precise mathematical reconstruction of the stochastic distribution characteristics of natural fractures, the apparent fracture distribution characteristics of 499 fractures in 12 standard specimens were investigated. The results show that there is a significant correlation among the density, length, and dip angle of fractures in different directions. Based on this, a quantitative description method for fracture networks that considers the relationship between fracture density and orientation is proposed. Combined with the Fisher model, the probability density distribution function of natural fracture orientation density was established. Using this method, the equivalent numerical analysis model of rock specimens containing natural fractures was reconstructed on the RFPA platform, and numerical experiments of triaxial loading and unloading were performed on the reconstructed equivalent fractured rock numerical model. This method can quantitatively describe the geometric distribution characteristics of fractures in natural rocks. The modified Fisher model enables the visual reconstruction of natural fracture networks, offering an effective technical approach for building equivalent numerical analysis models of rocks with natural fractures. It is highly valuable for studying the coupled mechanical behavior of multi‐physical fields in natural fractured rocks and provides an equivalent analysis method for visualizing and analyzing the damage process of natural fractured rocks.
{"title":"Mathematical Reconstruction Analysis of a Natural Fracture Network in Rock Based on a Modified Fisher Model and Its Numerical Realization","authors":"Qingci Qin, Chaoquan Luo, Kegang Li, Fa Dong, Naeem Abbas","doi":"10.1002/nag.70205","DOIUrl":"https://doi.org/10.1002/nag.70205","url":null,"abstract":"Fractures are one of the most critical factors influencing the mechanical properties of rocks. To explore the quantitative description method of fracture networks in natural rock masses and achieve precise mathematical reconstruction of the stochastic distribution characteristics of natural fractures, the apparent fracture distribution characteristics of 499 fractures in 12 standard specimens were investigated. The results show that there is a significant correlation among the density, length, and dip angle of fractures in different directions. Based on this, a quantitative description method for fracture networks that considers the relationship between fracture density and orientation is proposed. Combined with the Fisher model, the probability density distribution function of natural fracture orientation density was established. Using this method, the equivalent numerical analysis model of rock specimens containing natural fractures was reconstructed on the RFPA platform, and numerical experiments of triaxial loading and unloading were performed on the reconstructed equivalent fractured rock numerical model. This method can quantitatively describe the geometric distribution characteristics of fractures in natural rocks. The modified Fisher model enables the visual reconstruction of natural fracture networks, offering an effective technical approach for building equivalent numerical analysis models of rocks with natural fractures. It is highly valuable for studying the coupled mechanical behavior of multi‐physical fields in natural fractured rocks and provides an equivalent analysis method for visualizing and analyzing the damage process of natural fractured rocks.","PeriodicalId":13786,"journal":{"name":"International Journal for Numerical and Analytical Methods in Geomechanics","volume":"42 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145731499","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Giulia Capati, Diana Salciarini, Alessandro F. Rotta Loria
The subsurface undergoes temperature variations in many situations due to anthropogenic and natural causes, which strongly influence the long‐term behavior of soils. These phenomena can involve temperature anomalies in the ground across distances of a few meters, as in the case of nuclear waste repositories, to distances encompassing entire cities, as in the case of subsurface urban heat islands. To date, a number of constitutive models have been proposed to capture the mechanics of soils under non‐isothermal conditions, with particular attention to fine‐grained soils due to their renowned sensitivity to temperature variations. However, most of the available models suffer from many constitutive parameters that hinder their applicability to the analysis of large and complex problems involving thermally induced deformations of fine‐grained soils. This study extends the classical Kelvin–Voigt model with a temperature‐dependent formulation for capturing the reversible or irreversible thermally induced deformations of fine‐grained soils, interpreted through the theory of thermally accelerated creep. Implemented in a finite element software and validated against experimental data, the model shows that the thermally induced deformations of fine‐grained soils are highly sensitive to the temperature variation rate, while they are little influenced by the magnitude of the applied mechanical loads. The proposed model effectively captures the complex, time‐dependent deformations of fine‐grained soils with only a few easily calibrated parameters, making it a practical tool for the long‐term analysis of thermally induced creep in such materials.
{"title":"Extended Kelvin–Voigt Model for Simulating Thermally Accelerated Creep in Fine‐Grained Soils","authors":"Giulia Capati, Diana Salciarini, Alessandro F. Rotta Loria","doi":"10.1002/nag.70190","DOIUrl":"https://doi.org/10.1002/nag.70190","url":null,"abstract":"The subsurface undergoes temperature variations in many situations due to anthropogenic and natural causes, which strongly influence the long‐term behavior of soils. These phenomena can involve temperature anomalies in the ground across distances of a few meters, as in the case of nuclear waste repositories, to distances encompassing entire cities, as in the case of subsurface urban heat islands. To date, a number of constitutive models have been proposed to capture the mechanics of soils under non‐isothermal conditions, with particular attention to fine‐grained soils due to their renowned sensitivity to temperature variations. However, most of the available models suffer from many constitutive parameters that hinder their applicability to the analysis of large and complex problems involving thermally induced deformations of fine‐grained soils. This study extends the classical Kelvin–Voigt model with a temperature‐dependent formulation for capturing the reversible or irreversible thermally induced deformations of fine‐grained soils, interpreted through the theory of thermally accelerated creep. Implemented in a finite element software and validated against experimental data, the model shows that the thermally induced deformations of fine‐grained soils are highly sensitive to the temperature variation rate, while they are little influenced by the magnitude of the applied mechanical loads. The proposed model effectively captures the complex, time‐dependent deformations of fine‐grained soils with only a few easily calibrated parameters, making it a practical tool for the long‐term analysis of thermally induced creep in such materials.","PeriodicalId":13786,"journal":{"name":"International Journal for Numerical and Analytical Methods in Geomechanics","volume":"15 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145731502","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study proposes an efficient modeling approach for shield tunnel joints based on user‐defined elements (UELs), which is applied to the analysis of transverse deformation in shield tunnels. The element stiffness matrix of longitudinal joints with irregular geometric configurations was derived under arbitrary loading conditions. The solution procedure of the stiffness matrix was then incorporated into the UEL algorithm framework. The developed element simultaneously accounts for the varying load state at longitudinal joints, geometric configurations of the joint, and material nonlinearity, as well as their coupling effect on the load‐bearing capacity of the joint. Subsequently, the feasibility and accuracy of the UEL‐based modeling approach were evaluated across multiple modeling scales. The results demonstrate that this element not only significantly simplifies the modeling process but also effectively captures the nonlinear characteristics of tunnel convergence deformation observed in practical engineering scenarios. In addition, the UEL‐based modeling approach was employed to investigate the transverse deformation of shield tunnels subjected to an extreme surcharge–unloading–grouting rehabilitation sequence. Lining displacement–subgrade reaction and in situ stress state were appropriately incorporated into the numerical model. The effects of initial soil stiffness and the coefficient of earth pressure at rest on tunnel transverse deformation were quantitatively examined, along with the relationship between tunnel convergence and joint rotation. The results reveal a flag‐shaped hysteresis in the moment‐rotation response of tunnel joints under unloading and grouting, underscoring the importance of precisely capturing the multi‐degree‐of‐freedom coupling in joint element for practical engineering applications.
{"title":"An Efficient User‐Defined Element Framework for Joint Behavior Simulation and Transverse Deformation Analysis in Shield Tunnels","authors":"Hanwen Ji, Ximin Hu, Yu Miao, Hongjun He","doi":"10.1002/nag.70206","DOIUrl":"https://doi.org/10.1002/nag.70206","url":null,"abstract":"This study proposes an efficient modeling approach for shield tunnel joints based on user‐defined elements (UELs), which is applied to the analysis of transverse deformation in shield tunnels. The element stiffness matrix of longitudinal joints with irregular geometric configurations was derived under arbitrary loading conditions. The solution procedure of the stiffness matrix was then incorporated into the UEL algorithm framework. The developed element simultaneously accounts for the varying load state at longitudinal joints, geometric configurations of the joint, and material nonlinearity, as well as their coupling effect on the load‐bearing capacity of the joint. Subsequently, the feasibility and accuracy of the UEL‐based modeling approach were evaluated across multiple modeling scales. The results demonstrate that this element not only significantly simplifies the modeling process but also effectively captures the nonlinear characteristics of tunnel convergence deformation observed in practical engineering scenarios. In addition, the UEL‐based modeling approach was employed to investigate the transverse deformation of shield tunnels subjected to an extreme surcharge–unloading–grouting rehabilitation sequence. Lining displacement–subgrade reaction and in situ stress state were appropriately incorporated into the numerical model. The effects of initial soil stiffness and the coefficient of earth pressure at rest on tunnel transverse deformation were quantitatively examined, along with the relationship between tunnel convergence and joint rotation. The results reveal a flag‐shaped hysteresis in the moment‐rotation response of tunnel joints under unloading and grouting, underscoring the importance of precisely capturing the multi‐degree‐of‐freedom coupling in joint element for practical engineering applications.","PeriodicalId":13786,"journal":{"name":"International Journal for Numerical and Analytical Methods in Geomechanics","volume":"144 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145731501","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Frequent occurrences of shield clogging during slurry shield tunneling emphasize the necessity of optimizing cutterhead scouring systems. Conventional studies largely rely on empirical design and simplified analyses, which fail to capture complex flow–solid interactions or enable quantitative optimization. To overcome these limitations, a computational fluid dynamics (CFD) model was developed to simulate jet flow formation in shield nozzles and the flow field in the cutterhead excavation zone. It allows to systematically investigate the effects of nozzle inlet velocity, slurry chamber pressure, and cutterhead rotation speed, promoting the optimization of nozzle geometry and arrangement. The optimized configuration has been validated in the Qingdao Second Submarine Tunnel. Results show that increasing inlet velocity enhances jet strength without altering the overall velocity distribution pattern. Cutterhead rotation generates a rotating flow field that intensifies scouring but causes jet deflection, while interference between central and adjacent nozzles limits the effective scouring area. By modifying the outlet geometry and eliminating ineffective main arm nozzles, both the effective scouring area ratio and scouring efficiency index were improved. The optimized configuration ensures stable and efficient advancement when the nozzle inlet velocity exceeds 4 m/s, effectively preventing shield clogging. This work provides a validated modeling framework and practical optimization strategy for enhancing slurry shield performance in complex geological conditions.
{"title":"Optimizing Cutterhead Scouring Systems for Large‐Diameter Slurry Shields: A Case Study of the Qingdao Second Submarine Tunnel","authors":"Hanbiao Zhu, Shuying Wang, Zihao Jin, Jiazheng Zhong, Xiangcou Zheng, Pengfei Liu","doi":"10.1002/nag.70201","DOIUrl":"https://doi.org/10.1002/nag.70201","url":null,"abstract":"Frequent occurrences of shield clogging during slurry shield tunneling emphasize the necessity of optimizing cutterhead scouring systems. Conventional studies largely rely on empirical design and simplified analyses, which fail to capture complex flow–solid interactions or enable quantitative optimization. To overcome these limitations, a computational fluid dynamics (CFD) model was developed to simulate jet flow formation in shield nozzles and the flow field in the cutterhead excavation zone. It allows to systematically investigate the effects of nozzle inlet velocity, slurry chamber pressure, and cutterhead rotation speed, promoting the optimization of nozzle geometry and arrangement. The optimized configuration has been validated in the Qingdao Second Submarine Tunnel. Results show that increasing inlet velocity enhances jet strength without altering the overall velocity distribution pattern. Cutterhead rotation generates a rotating flow field that intensifies scouring but causes jet deflection, while interference between central and adjacent nozzles limits the effective scouring area. By modifying the outlet geometry and eliminating ineffective main arm nozzles, both the effective scouring area ratio and scouring efficiency index were improved. The optimized configuration ensures stable and efficient advancement when the nozzle inlet velocity exceeds 4 m/s, effectively preventing shield clogging. This work provides a validated modeling framework and practical optimization strategy for enhancing slurry shield performance in complex geological conditions.","PeriodicalId":13786,"journal":{"name":"International Journal for Numerical and Analytical Methods in Geomechanics","volume":"367 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145731500","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study presents a semi‐analytical solution for modeling suspended sediment distribution in turbulent flows within ice‐covered channels under unsteady, non‐equilibrium conditions. The solution is derived using the generalized integral transform technique (GITT). Validation was performed against the cell‐centered finite volume method and existing experimental data. The results confirm high accuracy, supported by error analysis. Optimized parameter values were obtained through a hybrid genetic and interior point algorithm. Several underlying phenomena of particle‐turbulence interactions in ice‐covered channels are explored. The focus is on the influence of key sediment transport parameters on the time‐dependent evolution of vertical concentration profiles of suspended sediment particles. Key findings indicate that increasing the settling‐velocity correction coefficient raises sediment concentration profiles over time. In contrast, greater ice‐cover roughness reduces sediment suspension. Sensitivity analysis highlights the inverse of the Schmidt number as a critical factor. This novel application of GITT and variance‐based sensitivity analysis (VBSA) provides a detailed solution library, and serves as a benchmark for numerical models.
{"title":"Suspended Sediment Transport in Ice‐Covered Turbulent Flow: Semi‐Analytical Solution and Parametric Sensitivity","authors":"Sourav Hossain, Ashok Das, Sanjib Naskar, Sweta Narayan Sahu, Koeli Ghoshal","doi":"10.1002/nag.70192","DOIUrl":"https://doi.org/10.1002/nag.70192","url":null,"abstract":"This study presents a semi‐analytical solution for modeling suspended sediment distribution in turbulent flows within ice‐covered channels under unsteady, non‐equilibrium conditions. The solution is derived using the generalized integral transform technique (GITT). Validation was performed against the cell‐centered finite volume method and existing experimental data. The results confirm high accuracy, supported by error analysis. Optimized parameter values were obtained through a hybrid genetic and interior point algorithm. Several underlying phenomena of particle‐turbulence interactions in ice‐covered channels are explored. The focus is on the influence of key sediment transport parameters on the time‐dependent evolution of vertical concentration profiles of suspended sediment particles. Key findings indicate that increasing the settling‐velocity correction coefficient raises sediment concentration profiles over time. In contrast, greater ice‐cover roughness reduces sediment suspension. Sensitivity analysis highlights the inverse of the Schmidt number as a critical factor. This novel application of GITT and variance‐based sensitivity analysis (VBSA) provides a detailed solution library, and serves as a benchmark for numerical models.","PeriodicalId":13786,"journal":{"name":"International Journal for Numerical and Analytical Methods in Geomechanics","volume":"9 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145731503","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yazhen Sun, Lifan Yuan, Jinchang Wang, Longyan Wang, Youlin Ye
A novel analytical approach based on the state‐space method (SSM) is proposed to facilitate the rapid and accurate analysis of the mechanical behavior of pipe umbrellas in shallow‐buried tunnels. First, a mechanical analysis model and its governing equations are developed based on the Winkler elastic foundation beam theory, incorporating key construction‐related factors such as the lag effect of primary support, differential stress release in the surrounding rock, and the elasto‐plastic behavior of the stratum. The governing equations are then transformed into a concise matrix form using the SSM and solved based on matrix theory and the continuity conditions between adjacent beam segments. Analytical solutions for deformation and internal forces at any cross‐section of the pipe umbrella are derived under the nonlinear interactions among the pipe umbrella, surrounding rock, and primary support. The accuracy and applicability of the proposed method are verified through comparisons with existing field monitoring data, analytical solutions, and numerical simulation results from other researchers. On this basis, taking the Aketepu Tunnel as a case study, the influences of the surrounding rock stiffness ahead of the tunnel face, excavation footage, steel pipe diameter, and other factors on the deformation and internal forces of the pipe umbrella were investigated, and a recommended design scheme was proposed accordingly. The scheme was subsequently applied in the field, and monitoring results showed that the maximum deformations at two sections were 26.1 and 22.3 mm, respectively, both within the acceptable limits for surrounding rock deformation control.
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